[components] fix import from dagster (#27321)

## Summary & Motivation

Fix mistaken import from `dagster` yaml utils instead of local
`dagster_dg` yaml utils.

## How I Tested These Changes

BK

Author: smackesey

python_modules/libraries/dagster-dg/dagster_dg/docs.py

@@ -5,10 +5,10 @@
 
 import markdown
 import yaml
-from dagster._utils.source_position import SourcePositionTree
-from dagster._utils.yaml_utils import parse_yaml_with_source_positions
 
 from dagster_dg.component import RemoteComponentType
+from dagster_dg.yaml_utils import parse_yaml_with_source_positions
+from dagster_dg.yaml_utils.source_position import SourcePositionTree
 
 REF_BASE = "#/$defs/"
 JSON_SCHEMA_EXTRA_REQUIRED_SCOPE_KEY = "dagster_required_scope"